[Bldg-sim] Streamlining CAD-to-Building Simulation Workflows

[Dennis Knight]

Thank All,
I have used ConstructDXF with some success when the 2D drawings are clean,
as suggested. However, if I’ve got a really clean “stick” drawing, its
about as easy just to use the IES geometry tools to draw the spaces from
scratch. The process I use to get clean floor plans quickly is use a 2D CAD
drawing, turn off all the layers I want to keep (walls, doors, windows,
space names), then select everything else and delete it, then turn the
layers I turned off, save as DXF, then use ConstructDXF or simply sketch
the plan using the attached DXF. This workflow works fairly well.


M. Dennis Knight, P.E., FASHRAE
Founder & Principal
*W*hole *B*uilding *S*ystems, LLC
P.O. Box 1845
Mt. Pleasant, SC 29465
Phone: 843-437-3647
Email: dknight at wholebuildingsystems.com
Website: www.wholebuildingsystems.com



On Thu, Sep 25, 2025 at 10:37 PM Karen Walkerman via Bldg-sim <
bldg-sim at lists.onebuilding.org> wrote:

> The approach we take in EP3 (https://ep3.solutions), is similar to
> Chris's description of creating "watertight" 2D CAD drawings. 2D floorplans
> are created, and then walls are extruded up to intersect with flat or
> pitched roofs.
>
> If you already have clean CAD drawings, you can translate them to EP3
> floors with one click.
>
> In EP3, instead of grouping 3D surfaces by space or zone, we maintain the
> 2D floorplans, and have exterior walls, interior walls, and roof surfaces.
> The major advantage is that changes to floorplans can be made in the 2D
> floorplans at any phase of the project.  Adjacent zone geometry, walls, and
> intersections with complex roof shapes happen automatically. This makes it
> much easier to adapt and update building geometry as a project moves from
> SD through to construction.
>
> While EP3 is primarily uses EnergyPlus as a simulation engine, we can also
> create eQuest geometry, constructions, schedules and internal loads.
>
> Best,
>
> Karen
>
> On Thu, Sep 25, 2025, 22:51 Chris Yates via Bldg-sim <
> bldg-sim at lists.onebuilding.org> wrote:
>
>> Hi Gurneet,
>>
>>
>>
>> There are many formats and geometry paradigms (E+ has several ways of
>> defining geometry). Some paradigms are based on simple collections of 3d
>> polylines, whilst others are a bit more “parametric” and therefore
>> predicated on some limitations (such as a single planar nGon defining the
>> floor).
>>
>>
>>
>> *IES*
>>
>> Commercially, I can only speak of how I hack geometry into my tool of
>> choice – IES VE. I’ve not found gbXML or IFC import very reliable to import
>> into IES. However, there’s a function called constructDXF that is very good
>> at extruding 2D cad plans into a 3d model. The cad plans have to be
>> super-clean, but I don’t mind this because I’m very happy working in CAD.
>> You need to create a stick drawing presenting watertight zones. Each zone
>> has a line of Dtext in the middle representing the zone name. It’s a bit
>> archaic and it’s generally not what they teach you on the training course!
>> I think constructDXF has been part of the software for almost 30 years!
>>
>>
>>
>> I believe the underlying geometry paradigm is 3d polylines. A “gem”
>> (geometry) file can be exported out of IES in ascii text format. The format
>> of this is definitely 3d polys.
>>
>>
>>
>> *IDA ICE*
>>
>> I also have some experience with IDA ICE. This tends to do a fairly
>> decent job of importing IFC files, as long as the zones are valid (good
>> luck with your architect). The zone definition appears to be more on the
>> “parametric” side with IDA – a typical zone is prismatic but features such
>> as a clipped roof can be applied. Max Tillberg at Equa has worked on a
>> number of workflows to get geometry into IDA apart from using IFC. From
>> what I understand, he’s had a degree of success using Rhino, Revit,
>> Speckle, and even the open-source tool, Blender.
>>
>>
>>
>> I hope that this helps.
>>
>>
>>
>> Kind regards
>>
>>
>>
>> Chris
>>
>>
>>
>> *From:* Bldg-sim <bldg-sim-bounces at lists.onebuilding.org> *On Behalf Of *Gurneet
>> Singh via Bldg-sim
>> *Sent:* 25 September 2025 10:15
>> *To:* bldg-sim <bldg-sim at lists.onebuilding.org>
>> *Subject:* [Bldg-sim] Streamlining CAD-to-Building Simulation Workflows
>>
>>
>>
>> Hi all,
>>
>> We’ve been exploring ways to reduce manual effort in transferring
>> geometry from CAD into building simulation formats like eQuest, gbXML, and
>> others. In our recent work, we developed a plugin that facilitates this
>> process by converting CAD lines directly into multiple simulation-ready
>> formats (eQuest, GBXML, HAP, Rhino), aiming to save time and minimize
>> errors.
>>
>> I’d be very interested in feedback from this group on workflow
>> improvements or challenges you’ve encountered when moving from CAD to
>> simulation formats—especially regarding geometry accuracy and
>> interoperability.
>>
>> Best regards,
>>
>> Gurneet Singh
>>
>> Director
>>
>>
>>
>> Environmental Design Solutions Pvt. Ltd.
>>
>> D-1/25,
>> <https://www.google.com/maps/search/D-1%2F25,+Vasant+Vihar,+New+Delhi+110057?entry=gmail&source=g>
>>
>> <https://www.google.com/maps/search/D-1%2F25,+%C2%A0+Vasant+Vihar,+New+Delhi+110057?entry=gmail&source=g>Vasant
>> Vihar, New Delhi 110057
>> <https://www.google.com/maps/search/D-1%2F25,+Vasant+Vihar,+New+Delhi+110057?entry=gmail&source=g>
>>
>>
>>
>> [m] +91 9899240140    [t]  +91 11 4056 8633
>>
>> gurneet at edsglobal.com | www.edsglobal.com
>>
>> Achieving water resilience with LEED Zero Water – setting a new standard
>> for sustainable water management!
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